a) Field of the Invention
This invention relates to a plant cultivation mat to be disposed, in particular, on artificial ground such as the roof-top of a building, veranda, terrace, and others for growing various plants (grasses) such as, in particular, lawn or other earth-covering plants, flowering plants, vegetables, and so forth.
b) Description of Prior Arts
It has heretofore been a practice, when growing plants at a place having a flat laying surface like the roof-top of a building, terrace, veranda, and others, to form a water-prevention layer and a root-protection layer, or to lay a sheet, on which soil is heaped up to grow lawn or other earth-covering plants, flowering plants, vegetables, and so forth (see: for example, laid-open gazette of Japanese patent application No. 4-99411).
It has also been a practice to lay square boxes (named plant cultivation mats or grass growing mats), each of which has an opening in its bottom part and is disposed in a recessed form with its top part being open upward, spread over the entire flat laying surface of the roof-top of a building, and others, followed by filling soil in the square boxes to grow various plants. Such plant growing facility possesses advantages such as easy laying and removal, and it can also be used in existing buildings.
With the abovementioned plant installation, however, when walkers walk on the top part of the soil as layed down, the level of the soil is lowered by the treading pressure of the walker to become solid and hard, with the consequent difficulty in walking on it. On the other hand, in the greening movement with use of lawn, which has become flourishing in recent years, in particular, free walking on the lawn is the requisite condition, hence the tendency is that public walkers should indispensably be permitted to walk on the top surface part of the soil at the plant (grass) growing facility.